In recent years, an obstacle detection device that detects an obstacle, such as a pedestrian and an obstacle, using a plurality of cameras, such as a stereo camera device, has been put to practical use. The stereo camera device is an image processing device that calculates a position deviation (parallax) of the same object on a plurality of images imaged at the same time, calculates a position of the object on a real space based on the parallax using a known conversion formula, and recognizes the object. The stereo camera device can be applied to a monitoring system that detects intrusion of a suspicious person or abnormality, or an onboard system that assists safety driving of vehicles (see PTL 1).